Toxoplasma gondii can stop cancer in its tracks as a vaccine

A healthy immune system responds vigorously to T. gondii in a manner that parallels how the immune system attacks a tumor.
In response to T. gondii, the body produces natural killer cells and cytotoxic T cells. These cell types wage war against cancer cells.
Cancer can shut down the body's defensive mechanisms, but introducing
T. gondii into a tumor environment can jump start the immune system.

Engineering T. gondii as a Cancer Vaccine

Since it isn't safe to inject a cancer patient with live replicating
strains of T. gondii, Bzik and Fox created "cps," an immunotherapeutic
vaccine. Based on the parasite's biochemical pathways, they delete a
Toxoplasma gene needed to make a building block of its genome and create
a mutant parasite that can be grown in the laboratory but is unable to
reproduce in animals or people. Cps is both nonreplicating and safe.
Even when the host is immune deficient, cps still retains that unique
biology that stimulates the ideal vaccine responses.
Published laboratory studies from the Geisel School of Medicine at
Dartmouth labs have tested the cps vaccine in extremely aggressive
lethal mouse models of melanoma or ovarian cancer and found
unprecedented high rates of cancer survival.
"Cps stimulates amazingly effective immunotherapy against cancers,
superior to anything seen before," said Bzik. "The ability of cps to
communicate in different and unique ways with the cancer and special
cells of the immune system breaks the control that cancer has leveraged
over the immune system."

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